Abstract: 【Objective】 To study the effects of temperature, humidity, rainfall and duration of rainfall on the occurrence and development of Grape Red Globe downy mildew in Yili River Valley of Xinjiang, and to provide the basis for reducing the application of chemical pesticides in the key period of control. 【Methods】 2012-2016, The epidemic situation of downy mildew such as the time of infecting the leaves and the degree of damage of the leaves were systematically monitored. 【Results】 The occurrence of grape downy mildew increased year by year. The incidence of downy mildew was different in different years, but the trend was the same. It began to occur in the middle and late of June. The disease index rose sharply in August, and kept stable when it reached the peak in the middle of September. There was a significant correlation between the onset of rainy season and the rainfall. 【Conclusion】 The epidemic performance index of Grape Downy Mildew in Grape Red Globe of Yili River Valley increased. According to the equation y = 73.263e^{0.190 9x}, R² = 0. 790,9, the forecast index of meteorological factors for the epidemic degree of grape downy mildew was determined. According to this model, the forecast results of the epidemic degree of downy mildew in the investigated vineyard from 2012 to 2016 are completely consistent with the actual situation.